Pigmented latex paints having superior gloss prepared by grinding a pigment into a solution of a copolymer of an unsaturated carboxylic acid

Abstract

A high gloss, water base, pigmented latex is provided by grinding a pigment into a water-free solution of a carboxyl-functional addition copolymer of monoethylenically unsaturated monomers including at least about 3% by weight of monoethylenically unsaturated carboxylic acid in water miscible organic solvent, the copolymer being at least partially neutralized with an amine, particularly an hydroxy amine, to render the said copolymer dispersible in water, and thereby form a nonaqueous pigment paste, and then mixing the nonaqueous pigment paste with an aqueoux latex. The invention includes the latex paint so-produced.

We claim: 
     
       1. A method of producing a high gloss, air drying water base, pigmented latex paint comprising grinding a pigment into a water-free solution of an at least partially neutralized carboxyl-functional addition copolymer of monoethylenically unsaturated monomers including at least about 3% by weight of monoethylenically unsaturated carboxylic acid in water miscible organic solvent, the major proportion of said pigment being titanium dioxide, and the pigment volume concentration being at least 10%, said copolymer being at least partially neutralized with an hydroxy amine having the formula: ##STR2## in which R is hydrogen or an alkyl group, R' is an alkylene group, and X is either R or R'OH, to render the said copolymer dispersible in water, and thereby form a nonaqueous pigment paste, and then mixing the nonaqueous pigment paste with an aqueous latex consisting essentially of emulsified aqueous emulsion copolymer particles having a T g  below 20° C. 
     
     
       2. A method as recited in claim 1 in which said hydroxy amine is a tertiary amine and said R and R' groups contain from 1-4 carbon atoms. 
     
     
       3. A method as recited in claim 1 in which said hydroxy amine is dimethyl ethanol amine. 
     
     
       4. A method as recited in claim 1 in which said carboxyl-functional addition copolymer is a solution copolymer and said water miscible organic solvent is used in an amount of from 10% to 150%, based on the weight of the solution copolymer. 
     
     
       5. A method as recited in claim 1 in which said copolymer contains up to about 40% of monoethylenically unsaturated carboxylic acid. 
     
     
       6. A method as recited in claim 5 in which said copolymer is a solution copolymer containing from 15-30% of monoethylenically unsaturated carboxylic acid, and said hydroxy amine is used in an amount to neutralize at least 50% of the acid groups in the copolymer. 
     
     
       7. A method as recited in claim 5 in which the monomers of said copolymer consist essentially of methyl methacrylate, styrene, vinyl toluene, or vinyl acetate, in combination with C 2  - C 8  alkyl ester of monoethylenically unsaturated carboxylic acid in addition to said acid. 
     
     
       8. A method as recited in claim 7 in which said copolymer monomers further include monoethylenically unsaturated hydroxy monomer or monoethylenically unsaturated amide monomer. 
     
     
       9. A method as recited in claim 1 in which said emulsion copolymer is selected from vinyl acetate-butyl acrylate copolymers, vinyl acetate-ethylene copolymers, and methyl methacrylate-ethyl acrylate copolymers. 
     
     
       10. The high gloss, water base, pigmented latex paint produced by the method of claim 1.